For example, if I want to create something to monitor and auto water my garden. I don't want to have a laptop sitting outside 24/7 or a line inside and require my desktop PC on 24/7.

So youre running an entire Linux environment to turn a relay/solenoid on and off?

Now imagine you’re a kid who had the idea to water your garden with a computer. On an arduino, you’d write about 20 lines of code.

On a PI...I mean, how do you even get a computer program to run at boot? What’s a computer program? Okay I have a .img file now what? Python? But some people say I should use $somethingelse. Okay I need another monitor to connect to it? Open up my router and find a DHCP entry so I can SSH into it? What do ANY of those words mean?

“Oh well I’ll get to it someday.”

Don’t get me wrong, I have plenty of raspberry pis in many different projects, and in fact I’d make a strong wager that I have deployed more raspi projects than most people who consider themselves huge raspi fans. For SOME things there isn’t a substitute. For most things they’re extremely discouraging.

I don't understand your comment. Yes, you could do it with an Arduino too, or any other computer, or a microcontroller.

From my experience, RPi might be more appealing since it runs a real OS and you can have a desktop environment.

What is "Idle" (link?)? thanks!

IDLE is a Python code editor, REPL, and runner. Ships with Python by default.

Wow, never knew that was there. Learn something new everyday. Thanks!